Preparation of ceramic frit compositions



United States Patent PREPARATION OF CERAMIC FRIT COMPOSITIONS Malcolm D. Beals, Fanwo'od, N.J., and Edward A. Giess,

Wappingers Falls, N.Y., assignors to National Lead 1 Company, New York, N.Y., a corporation of New Jersey No Drawing. Application January 12, 1959 Serial No. 786,013

6 Claims. (Cl. 106-49) :must exhibit certain properties. It is necessary, first of all, for the glaze to have a coefficient of thermal expansion similar to that of the substrate ceramic material; :otherwise undue stresses will be set up during the cooling of the fired pieceresulting in spalling, cracking, chipping or crazing. Aside from the necessary limitations on the .eoefiicient of expansion, other properties are desirable in a decorative glaze. Among these may be mentioned high opacity, gloss, durability at moderate maturing temperature, and purity of color. Particularly in the case of a white glaze, a pure white color is to be desired. Such'a base color lends itself readily to the production, if desired, of pastel shades by the addition of minor amounts of tinting agents to the formulation.

It is, therefore, an object of the present invention to provide a frit composition from which an improved ceramic glaze can be produced. It is a further object to ,provide a frit composition from which a ceramic glaze {having a coefficient of expansion comparable to the co- .efficient of expansion of the ceramic material to which it is applied, may be obtained. An additional object is to obtain a frit composition from which a durable white ceramic glaze ofihignopacitymay be obtained. 'These and other objects will become apparent from the more complete description of the instant invention.

In its broadest aspects, thisinvention contemplates a hit composition adaptable for preparation of self-opacified "ceramic glazes consisting essentially of Si in amount from about 50 to about 68 mole percent, A1 0 in amount from about 4 to about 12 mole percent, "H0 in amount from about 6 to about 18 mole percent, ZrO in amount from 0 to 6 mole percent, alkali metal oxide selected from .the group consisting ofNa O and K 0, said alkali metal oxide in amount from about 4 to about 18 mole percent -in which theNa O is .presentinamount of at least about 3 mole percent, alkaline earth metal oxide selected from the group consisting of CaO, MgO and SrO, said alkaline earth metaloxide in amount from about to about 15 mole percent.

A desirable embodiment of the instant invention con- .templates a frit composition of the above type in which ice and other oxides may be replaced on a mole basis up to /3 of the alkaline earth metal oxide in the composition.

It is also desirable in some instances to add, in addition to the above compositions, fluorine in an amount up to 6 mole percent. P 0 may also be added if desired in amount up to 4 mole percent. Lithium oxide may also be substituted for the sodium oxide in amount upto of the sodium oxide on a mole basis.

These frits which have the compositions as described may be used to produce ceramic glazes which are of commercial value. The ceramic glazes prepared from such frits may be applied to common ceramic materials such as wall tile, terra cota, earthenware and structural clay bodies. These compositions mature at temperatures in .the neighborhood of 950-l200 C. ;to produce highly opaque durable white glazes. These glazes are of the recrystallizing type by which is meant that they are pigmented by precipitation during the maturing heat of titania originally present as a melted-in constituent of the frit. The titanium values usually precipitate in these compositions as titanates and titanosilicates;

They may be applied by preparing a frit having a composition within the ranges above specified, fusing the batch to provide complete intersolution, quenching in water and milling. The milled frit, usually with the addition of small amounts of clay and electrolytes, is applied to the ceramic substrate in any ordinary manner such as by dipping, brushing or spraying.

In order to more fully illustrate the instant invention, the following examples are presented.

EXAMPLE IV A frit composition was prepared by melting together for about one hour, at about 1380 C., a mixture of the The calculated composition of the resulting frit, expressed in mole percentages, was as follows:

Component: Mole percent SiO 58.0 A1 0 8; 0 CaO 8.0 Na O 9.0 K 0 5.0 TiO 12.0

Whencomplete intersolutionwas achieved, and the frit composition was clear, the frit was quenched in water. One hundred parts of this quenched frit were ballmilled for 18 hours along with 4 :parts of clay, 025 part of NaNO 0.25 part of K -CO and 40 parts of demineralized water. The milled frit was then strained through a 200 mesh screen to insure the absence of any coarse particles. The strained slip was well dispersed and of sprayable consistency.

The milled slip was then sprayed onto a bisqued wall tile panel at a dry application weight ofabout 50 grams per square foot, dried for several hours at C. and then fired under oxidizing conditions (air atmosphere) at 1100 C. The kiln required about seven hours to,

reach this temperature, and after being held at the maximum temperature for-about one-half hour, heating was discontinued and the kiln was allowed to'cool overnight.-

The resulting glaze was smooth, glossy, continuous and Table IContinued possessed an excellent white color.

EXAMPLES 2-16 Mole Pereents Using the same procedure as that described in Exam- Fm Composition Examples pie 1, other frit compositions were prepared by mlxing various quantities of ingredients to produce frits having 7 8 9 10 n a variety of compositions which fall within the ranges contemplated by the mstant inventio rand ceramic glazes 6L0 5&7 5&0 5&0 58",) were prepared from such frit compositions. The amounts 0. 7. 7 0. 0 8.0 8. 0 of ingredients employed and the frit compositions 0b- 31 3:; 8 318 8'8 tained along with the smelting and firing temperatures 5.2 4.3 5.0 5.0 5.0 are recorded with the data of Example 1 in Table 1. &3 %3 The same examples expressed in weight percentages are 1.0 recorded in Table II. M

EXAMPLE 17 smelting Temp. (0. 1,330 1,350 1,330 1,400 Firing Temp. (c.) 1,075 1,150 1 050 1,050 In this example the same procedure as that described in Example 1 was employed except that smaller amounts of alkali metal oxides and higher amounts of silica were used. In preparing the frit composition the ingredients P t b W i ht were melted at 1525 C. at S y eg The vitreous glaze produced on the substrate using this frit composition possessed a very high reflectance with mgrqdlents Added Examples an excellent white color. The operational data are re 12 13 14 15 16 17 corded in Tables I and II.

110.0 110.0 110.0 110.0 100.8 Tabe 33 0;

1. .0 2. 1 OPERATING DATA OF FRIT COMPOSITIONS 2&0 2&0 2L8 138 5'9 0 b 20.0 20.7 25.3 20.7 55.0 Strontium a: onate Parts by Weight cadmium Oxide 8. 5

Lithium Carbonate 6.3 Zirconium Oxide 24. 6 Ingredients Added Examples Monobasic Sodium Phosphatn 18 4 Titanium Dioxide 32 0 32 0 10.0 32 0 35.4 1 2 3 4 5 6 Zing oarhnnahe 6, 3

Potter's Flint 110.0 113.0 110.0 110.0 110.0 113.0 Aluminum Oxide 27.2 34.0 27.2 27.2 27.2 34.0 Sodium Carbonate" 31.8 31.1 31.8 31.8 32.5 31.1 Potassium Carbonate- 23.0 22.0 23.0 23.0 23.5 22.0 Calcium Carbonate 20.7 20.1 20.0 20.0 27.4 M016 Percellts Magnesium Carbonate"- 5.6 21.9 Basic Lead Carbonate (PbOO );Pb(OI-I) 17,2 Frit Composition Examples Titanium Dioxide 32.0 32.0 32.0 32.0 20.0 32.0

53.0 53.0 55.1 53.0 030 Mole Percents 3.0 3.0 10.0 8.0 05 s3 52 52 is rit Composition Examples 5. 0 5. 0 4. 7 3. 0 0. 9 12.0 0.0 12.0 12.0 9.0

2.0 0-3 33 3s 38 2-5 1 0 713 010 1 2:3 2:8 1 j 233 smelting Temp. (0.) 1,400 1,330 1,480 1,400 1,525 12.0 12.0 12.0 12.0 10.0 12.0 e p-( 1 050 1,050 1,125 1.050 ,1 0

smelting Temp. (0.)- 1, 330 1,430 1,330 1,410 1,440 1,400 Firin Temp. (0.) 1,100 1,100 1,100 1,050 1 100 1,100

Table II Parts by Weight 1 Weight Percent:

Ingredients Added Examples Examples Potters Flint 122.0 111.4 110.0 110.0 110.0

lurnuium Oxide" 20.4 20.2 20.4 27.2 27.2 52.0 40.3 53.3 50.7 55.4 50.5 sodium Carbonate--. 33.2 10.2 17.7 31.3 31.3 12.2 11.5 12.2 15.2 0.2 11.0 Potassium Carbonate 24.0 22.1 23.0 23.0 23.0 5.0 4.7 6.9 7.1 6.5 Calcium Carbonate 28.0 25.7 46.7 20.0 20.0 8.3 7.9 8.5 8.2 8.8 8.1 M gnesium Carbonate. 2.8 2.8 7.0 6.7 7.2 6.9 7.4 6.8 arium Carbonate... 0. 14.3 13.0 11.9 14.3 12.1 13.0 inc Carb0nete 4 2 1.2 4.7 Sodium Flnoride 6.3 itanium Dioxide... 20.0 30.0 32.0 32.0 32.0 2.3

Table II-Continued Weight Percents Frlt Comp. Examples 51. 1 51. 7 47. 2 50. 6 49. 8 47. 4 53. 2 64. 5 12. 12. 1 12. 2 11. 9 11. 7 14. 6 12. 7. 3 4.9 5.0 4.9 6.4 6.1 6.9 9.9 8. 2 8. 2 7. 6 8. 1 8.0 7. 6 6. 6 3. l) 6.9 7.0 6.4 6.9 6.7 6.4 4.3 1.3 14.1) 14% 13. 3 13. 9 6. 8 l3. 8 14. 7 11. 3 2:2 III: III: 1.2 1. 3 11. 3 3. 7 4.1 1. 8 8 10. 6

In all of these examples the composition of the frit has been varied to show specific examples which fall within the ranges of composition which are contemplated by the instant invention. In these examples various glazes were produced from all of the frits produced and in every case the ceramic glazes produced were smooth, glossy and continuous and possessed an excellent white color.

From the above description and by the examples presented, frit compositions of various compositions have been produced and ceramic glazes have been prepared from such frit compositions. The glazes produced have an excellent white color. They are durable, possess high gloss, are highly opacified and have coeflicient of expansion which are useful for a variety of ceramic materials. The ceramic glazes produced possess pure white colors and such glazes render themselves readily as base glazes for the production of pastels by the addition of minor amounts of tinting agents to the formulation.

While this invention has been described and illustrated by the examples shown, it is not intended to be strictly limited thereto, and other modifications and variations may be employed within the scope of the following claims.

We claim:

1. A frit composition adaptable for preparation of selfopacified ceramic glazes consisting essentially of Si0 in amount from about to about 68 mole percent, A1 0 in amount from about 4 to about 12 mole percent, TiO in amount from about 6 to about 18 mole percent, ZrO in amount from 0 to 6 mole percent, alkali metal oxide selected from the group consisting of Na O and K 0, said alkali metal oxide in amount from about 4 to about 18 mole percent in which the Na O is present in amount of at least about 3 mole percent, alkaline earth metal oxide selected from the group consisting of CaO, MgO and SrO, said alkaline earth metal oxide in amount from about 5 to about 15 mole percent.

2. Composition according to claim 1 in which a compound selected trom the group consisting of BaO, PbO, CdO and ZnO is also present in said mixture, said compound replacing on a mole basis up to one-third of the alkaline earth metal oxide in said composition.

3. Composition according to claim 1 in which said composition also contains F in amounts up to 6 mole percent.

4. Composition according to claim 1 in which said composition also contains P 0 in amounts up to 4 mole percent.

5. Composition according to claim 1 in which said composition also contains Li O, said compound replacing on a mole basis up to of the sodium oxide.

6. Composition according to claim 1 in. which PbC) is also present in said mixture, said PbO replacing on a mole basis up to one-third of the alkaline earth metal oxide in said composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,393 Baldwin Oct. 4, 1949 2,498,912 Claudet Feb. 28, 1950 2,556,896 Beatty et al. June 12, 1951 FOREIGN PATENTS 901,258 France Oct. 30, 1944 

1. A FRIT COMPOSITION ADAPTABLE FOR PREPARATION OF SELFOPACIFIED CERAMIC GLAZES CONSISTING ESSENTIALLY OF SIO2 IN AMOUNT FROM ABOUT 50 TO ABOUT 68 MOLE PERCENT, AL2O3 IN AMOUNT FROM ABOUT 4 TO 12 MOLE PERCENT, TIO2 IN AMOUNT FROM ABOUT 6 TO ABOUT 18 MOLE PERCENT, ZRO2 IN AMOUNT FROM 0 TO 6 MOLE PERCENT, ALKALI METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF NA2O AND K2O, SAID ALKALI METAL OXIDE IN AMOUNT FROM ABOUT 4 TO ABOUT 18 MOLE PERCENT IN WHICH THE NA2O IS PRESENT IN AMOUNT OF AT LEAST ABOUT 3 MOLE PERCENT, ALKALINE EARTH METAL OXIDE SELECTED FROM THE GROUP CONSISTING OF CAO, MGO AND SRO, SAID ALKALINE EARTH METAL OXIDE IN AMOUNT FROM ABOUT 5 TO ABOUT 15 MOLE PERCENT. 